1. Field of the Invention
The present invention relates to a filter-drier which carries out mixing, reacting, filtering, washing and drying industrial chemicals or drugs such as antibiotics within a single processing vessel. Particularly, the present invention relates to an opening/closing device for a discharge hole of the filter-drier, in which an outer shell of a driving means for driving the opening/closing device of the discharge hole is sealed, so that during the discharge of the processed powders, the processed powders can be prevented from being introduced into the outer shell.
2. Description of the Prior Art
Conventionally, there are known many kinds of opening/closing devices for the discharge hole of the filter-drier. However, the outer shell of the driving means which opens or closes the discharge hole is not sealed. Therefore, when the processed drug powders are discharged out of the filter-drier, the fine drug powders are scattered to around the driving means of the opening/closing plate to adhere on the plate. Thus much of the valuable drug powders are lost, and the cleaning of the plate is troublesome.
One of the conventional opening/closing devices will be taken as an example.
Japanese Patent Gazette No. Sho-60-7930 (dated Feb. 28, 1985) discloses a discharge device of a filter-drier constituted as follows. A discharge hole is formed at the center of the bottom of a processing vessel, and a warhead shaped discharge tube moves up and down above the discharge hole. Around the discharge tube, there are formed a plurality of outlet holes. Thus if the discharge tube moves up into the processing vessel, the processed drug powders are discharged through the outlet holes, while if the discharge tube moves down, the discharge hole is closed by the head of the discharge tube.
This discharge device constituted as described above works smooth in the case of liquid materials. However, in the case of powdered materials, the processed powders adhere on around the discharge tube. It is a troublesome task to remove the adhered powders, and therefore, the adhered materials remain always within the filtering vessel.
Meanwhile, Japanese Patent Gazette No. Sho-58-35726 (dated Aug. 4, 1983) discloses a discharge device of the filtering vessel constituted as follows. A discharge hole is formed at the center of the bottom of the processing vessel, and a discharge tube is disposed beneath the discharge hole. Further, a warhead shaped opening/closing plate is formed at the center of the discharge tube, and the warhead shaped opening/closing plate moves up and down to open or close the discharge hole.
In this device, if the opening/closing plate moves down, the discharge hole is opened. However, the drug powders are accumulated on the opening/closing plate, and therefore, the cleaning is difficult, while the expensive drug powders are lost very much.
Meanwhile, another conventional discharge device of the filter-drier is illustrated in FIG. 3. In this discharge device, a tapered outer shell 2 of an opening/closing plate driving means A is detachably fastened onto a discharge tube 1 by means of a fastening device 2a. A motor 5 which actuates an opening/closing plate 3 is fixed on an end portion of the outer shell 2 of the driving means A. A screw shaft 6 which is threadably coupled with a nut 6b of a movable tube 6a is made to revolve at a slow speed by the motor 5 and a reduction device 5a. A sliding protuberance 7a of the movable tube 6a is guided along a guide groove 7a of a guide tube 7 without being rotated. The movable tube 6a moves back and forth in accordance with the revolutions of the screw shaft 6. The opening/closing plate 3 is fastened by means of a fastening device 3a to the leading end of the movable tube 6a, so that a discharge device 4 can be opened or closed in accordance with the back-and-forth movements of the movable tube 6a. A bellows 8 is formed around the guide tube 7, so that the lubricant would not be leaked from the screw shaft 6.
The conventional discharge device of FIG. 3 is useful both for liquid and powdered materials. Further, the movements of the agitating blades which are installed within the filter-drier are not interfered by the discharge device. However, the discharge hole 4 faces toward the outer shell 2 of the driving means of the opening/closing plate 3, and the inner portion of the outer shell 2 is open. Therefore, when the processed drug powders are discharged through the discharge hole, a part of the processed drug powders is introduced into the interior of the outer shell 2. Because of this leakage, the outer shell 2 has to be detached from the discharge tube 1 after each discharge of the drug powders so as to be cleaned, this being a troublesome task. When the cleaning is carried out, the expensive drug powders are lost very much, and therefore, it is difficult to efficiently process the drugs.